The present invention relates to an improved electrical installation for a fire engine, rotating derrick, crane, or the like, mounting a rotatable tower.
By way of background, certain types of fire engines have a ladder tower mounted on the rear thereof. The ladder tower permits a man to climb the ladder and the ladder tower also contains a water conduit terminating at a nozzle at the upper end of the tower for directing water at a fire. The electrical connections between a fire engine body and the tower consists of many wires, generally about 20, for the purpose of providing remote nozzle controls, remote ladder controls, and for an intercommunication system. During the course of using the ladder tower it is rotated about a vertical axis. Therefore, the electrical connections between the fire engine body and the ladder tower have to be of the type which permit such rotation. In the past, a slip ring system was used, as is common between a rotatable part and a stationary part. However, the slip rings in the present environment were subject to certain shortcomings. The slip rings were subject to dirt and therefore could occasionally fail to complete a circuit. In addition, they were subject to corrosion and wear and misadjustment so that the desired dependability of electrical communication was not achieved. Furthermore, the same problem existed relative to rotating derricks, cranes and analogous devices. It is with the overcoming of the foregoing deficiencies of electrical installations in devices of the foregoing type that the present invention is concerned.